A heat-dissipation fan is mainly used to produce forced air flow at a place requiring heat dissipation, so as to remove heat from the place. The heat-dissipation fan includes a rotor and a stator. When a magnetic field-induced excitation occurs between the rotor and the stator, the rotor is caused to rotate and the fan operates to produce air flow.
The rotor of the heat-dissipation fan mainly includes a shaft and a fan wheel hub having a plurality of blades formed thereon, which are assembled to each other. The stator is arranged on around an outer side of a bearing cup, i.e. a central tube, on a frame of the heat-dissipation fan to correspond to the fan wheel hub. Generally, the bearing cup of the fan is integrally formed with the fan frame through injection molding. There are also heat-dissipation fans that use a copper bearing cup, which is riveted to a base of the fan frame. However, the riveting process tends to damage the fan structure. In case of an incomplete riveting, the bearing cup tends to easily become loosen from the base of the fan frame. In addition, it is difficult to control the concentricity between the copper bearing cup and the base of the fan frame because the copper bearing cup is press-fitted into the base of the fan frame during the riveting process. Another disadvantage of using the riveted copper bearing cup is the loosen copper bearing cup will produce noise during fan operation.
It is therefore tried by the inventor to develop an improved fan central tube coupling structure to overcome the disadvantages of the conventional ways of connecting the bearing cup to the fan frame.